[1] We introduce a tool to determine surface fluxes from atmospheric concentration data in the midst of distributed sources or sinks over land, the Stochastic Time-Inverted Lagrangian Transport (STILT) model, and illustrate the use of the tool with CO 2 data over North America. Anthropogenic and biogenic emissions of trace gases at the surface cause large… (More)

[1] Ecosystem CO 2 exchange and atmosphere boundary layer (ABL) mixing are correlated diurnally and seasonally as they are both driven by solar insulation. Tracer transport models predict that these covariance signals produce a meridional gradient of annual mean CO 2 concentration in the marine boundary layer that is half as strong as the signal produced by… (More)

— To support real-time applications such as Voice-over-IP within a 802.11 Wireless LAN, efficient handoff mechanisms are required when a mobile client moves from one Access Point to another. In this paper, we present the design, implementation and performance results of MAC layer (layer-2) handoff algorithms which implement make-before-break mechanisms at… (More)

In this paper, we demonstrate a technique called active probing used to study TCP implementations. Active probing treats a TCP implementation as a black box, and uses a set of procedures to probe the black box. By studying the way TCP responds to the probes, one can deduce several characteristics of the implementation. The technique is particularly useful… (More)

[1] We present the Vegetation Photosynthesis and Respiration Model (VPRM), a satellite-based assimilation scheme that estimates hourly values of Net Ecosystem Exchange (NEE) of CO 2 for 12 North American biomes using the Enhanced Vegetation Index (EVI) and Land Surface Water Index (LSWI), derived from reflectance data of the Moderate Resolution Imaging… (More)

[1] We present a general framework for designing and analyzing Lagrangian-type aircraft observations in order to measure surface fluxes of trace gases on regional scales. Lagrangian experiments minimize uncertainties due to advection by measuring tracer concentrations upstream and downstream of the study region, assuring that observed concentration changes… (More)

Imperfect representation of vertical mixing near the surface in atmospheric transport models leads to uncertainties in modelled tracer mixing ratios. When using the atmosphere as an integrator to derive surface-atmosphere exchange from mixing ratio observations made in the atmospheric boundary layer, this uncertainty has to be quantified and taken into… (More)

[1] A conceptual framework is developed using atmospheric measurements from aircraft to determine fluxes of CO 2 from a continental land area. The concepts are applied to measurements of CO 2 , O 3 , and CO concentrations from the Amazon Boundary Layer Experiment (ABLE-2B, April–May 1987) to estimate fluxes of CO 2 for central and eastern Amazonia late in… (More)